Hereditary essential tremor-6 (ETM6) is an autosomal dominant neurologic disorder characterized by adult-onset kinetic and/or postural tremor usually affecting the upper limbs. Some patients may have involvement of the head, trunk, lower limbs, and/or voice. Additional neurologic features, such as cognitive impairment or pyramidal signs, are usually not observed. Brain imaging does not show cerebellar atrophy or leukodystrophy. Skin biopsy shows intranuclear eosinophilic inclusions in fibroblasts and sweat gland cells, which may be used for diagnosis. There is evidence of genetic anticipation, with progressive earlier age at onset in younger generations. In rare cases, the phenotype may convert to NIID over time (summary by Sun et al., 2020; Ng et al., 2020).
For a phenotypic description and a discussion of genetic heterogeneity of hereditary essential tremor, see ETM1 (190300). [from
OMIM]